Redux action (fetch from db) not firing when useEffect() is called - redux

Question

I am trying to build an eCommerce website to learn Redux.
At the moment I am trying to fetch the categories when the component mounts. Since I am using functional components, I understood that this is achieved by calling the useEffect() method.
Also, I am using json-server as a REST Api.
I am quite sure I have managed to compose my enhancers to pass to the store (dev tools and thunk), created actions, reducers and all.
My problem is that the action doesn't fire when the component mounts.
N.B. before introducing the Middleware and therefore the fetch request, everything worked just fine. Also consider that the fetch request is successful.
Hereafter is the code involved.
'src/index.js'
import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import * as serviceWorker from './serviceWorker';
import { createStore, applyMiddleware, compose } from 'redux'
import { Provider } from 'react-redux'
import rootReducer from './reducers'
import thunk from 'redux-thunk'
const composedEnhancers = compose(applyMiddleware(thunk), window.__REDUX_DEVTOOLS_EXTENSION__ && window.__REDUX_DEVTOOLS_EXTENSION__())
const store = createStore(
rootReducer, /* preloadedState, */
composedEnhancers
);
ReactDOM.render(
<Provider store={store}>
<React.StrictMode>
<App />
</React.StrictMode>
</Provider>,
document.getElementById('root')
);
// If you want your app to work offline and load faster, you can change
// unregister() to register() below. Note this comes with some pitfalls.
serviceWorker.unregister();
the action type in 'actions/index.js':
export const FETCH_CATEGORIES = 'FETCH_CATEGORIES'
the action creator in 'actions/index.js':
export const fetchCategories = () => (dispatch) => {
fetch("http://localhost:7000/categories")
.then(response => response.json())
.then(categories => {
return {
type: FETCH_CATEGORIES,
payload: categories
}
})
}
'reducers/index.js'
import * as actions from './../actions'
const initState = {
categories: [],
currentCategory: 'any',
toggler: 'hidden'
}
const rootReducer = (state = initState, action) => {
switch (action.type) {
case actions.SELECT_CATEGORY:
return { ...state, currentCategory: action.payload.value }
case actions.FETCH_CATEGORIES:
return { ...state, categories: action.payload }
case actions.TOGGLE:
return { ...state, toggler: action.payload.toggler }
default:
return state
}
}
export default rootReducer
the 'Filter.js' component
import React, { useEffect } from 'react';
import { connect } from 'react-redux'
import { selectCategory, fetchCategories } from '../../../../actions'
const Filter = (props) => {
// const [minPrice, setMinPrice] = useState(0)
// const handleMinPrice = event => {
// setMinPrice(event.target.value)
// }
// const [maxPrice, setMaxPrice] = useState(0)
// const handleMaxPrice = event => {
// setMaxPrice(event.target.value)
// }
// const [department, setDepartment] = useState("select")
// const handleDepartment = event => {
// console.log(event.target.value)
// setDepartment(event.target.value)
// }
// console.log(props);
const handleChange = event => {
event.preventDefault()
props.selectCategory(event.target.value)
}
useEffect(() => {
props.fetchCategories()
})
return (
<div className="filter-form col-12">
<form id="filter-category">
<label htmlFor="category">Category</label>
<select className="col-12" id="category" name="category" size="5" value={props.currentCategory} onChange={(event) => handleChange(event)}>
{props.categories.map(category => <option key={category.value} value={category.value}>{category.name}</option>)}
</select>
</form>
{props.currentCategory !== 'any' && <form id="filter-department">
<label htmlFor="department">Department</label>
<select className="col-12" id="department" name="department" size="5" value='{department}' onChange='{handleDepartment}'>
<option value="select">--- Select ---</option>
<option value="desktop PCs">Desktop PCs</option>
<option value="laptops">Laptops</option>
<option value="gamepads">Gamepads</option>
<option value="headphones">Headphones</option>
<option value="microphones">Microphones</option>
<option value="keyboards">Keyboards</option>
</select>
</form>}
{/* <form id="filter-price">
<label htmlFor="minimum-price">Min. Price: {minPrice}£</label>
<input type="range" min="1" max="100" value={minPrice} className="slider col-xs-12" id="minimum-price" onChange={handleMinPrice} />
<label htmlFor="maximum-price">Max. Price: {maxPrice}£</label>
<input type="range" min="100" max="1000" value={maxPrice} className="slider col-xs-12" id="maximum-price" onChange={handleMaxPrice} />
</form> */}
</div>
);
}
const mapStateToProps = (state) => {
return {
categories: state.categories,
currentCategory: state.currentCategory
}
}
const mapDispatchToProps = (dispatch) => {
return {
selectCategory: (value) => {
dispatch(selectCategory(value))
},
fetchCategories: () => {
dispatch(fetchCategories())
}
}
}
export default connect(mapStateToProps, mapDispatchToProps)(Filter);
Also, here is 'db.json'
{
"categories": [
{
"id": "1",
"value": "any",
"name": "--- Any ---",
"departments": []
},
{
"id": "2",
"value": "computers-and-accessories",
"name": "Computers and Accessories",
"departments": [
{
"id": "1",
"value": "desktop-pc",
"name": "Desktop PCs"
},
{
"id": "2",
"value": "laptops",
"name": "Laptops"
},
{
"id": "3",
"value": "keyboards",
"name": "Keyboards"
},
{
"id": "4",
"value": "headphones",
"name": "Headphones"
},
{
"id": "5",
"value": "mouses",
"name": "Mouses"
},
{
"id": "6",
"value": "gamepads",
"name": "Gamepads"
}
]
},
{
"id": "3",
"value": "fashion",
"name": "Fashion",
"departments": [
{
"id": "1",
"value": "dresses",
"name": "dresses"
},
{
"id": "2",
"value": "shoes",
"name": "Shoes"
},
{
"id": "3",
"value": "pants",
"name": "Pants"
},
{
"id": "4",
"value": "sunglasses",
"name": "Sunglasses"
},
{
"id": "5",
"value": "handbags",
"name": "Handbags"
},
{
"id": "6",
"value": "hats",
"name": "Hats"
}
]
},
{
"id": "4",
"value": "digital-music",
"name": "Digital Music",
"departments": [
{
"id": "1",
"value": "rock",
"name": "Rock"
},
{
"id": "2",
"value": "pop",
"name": "Pop"
},
{
"id": "3",
"value": "house-and-techno",
"name": "House and Techno"
},
{
"id": "4",
"value": "trap",
"name": "Trap"
},
{
"id": "5",
"value": "indie",
"name": "Indie"
},
{
"id": "6",
"value": "hip-hop",
"name": "Hip-Hop"
}
]
},
{
"id": "5",
"value": "house",
"name": "House",
"departments": [
{
"id": "1",
"value": "kitchen",
"name": "kitchen"
},
{
"id": "2",
"value": "garden",
"name": "Garden"
},
{
"id": "3",
"value": "bedroom",
"name": "Bedroom"
},
{
"id": "4",
"value": "bathroom",
"name": "Bathroom"
},
{
"id": "5",
"value": "livingroom",
"name": "Livingroom"
},
{
"id": "6",
"value": "cleaning",
"name": "Cleaning"
}
]
},
{
"id": "6",
"value": "grocery",
"name": "Grocery",
"departments": [
{
"id": "1",
"value": "vegetables",
"name": "Vegetables"
},
{
"id": "2",
"value": "pasta and rice",
"name": "Pasta and Rice"
},
{
"id": "3",
"value": "snacks",
"name": "Snacks"
},
{
"id": "4",
"value": "canned-food",
"name": "Canned Food"
},
{
"id": "5",
"value": "frozen",
"name": "Frozen"
},
{
"id": "6",
"value": "dairy",
"name": "Dairy"
}
]
}
]
}
What am I missing here?

Answer 1

Try dispatching like this in the action which will fire the reducer FETCH_CATEGORIES:
export const fetchCategories = () => (dispatch) => {
fetch("http://localhost:7000/categories")
.then(response => response.json())
.then(categories => {
// **Changes start here
dispatch ({
type: FETCH_CATEGORIES,
payload: categories
})
// **Changes end here
})
}